1. Field of the Invention
The present invention relates to a longwall coal cutting and loading machine for mining coal in longwalling operations, with a machine body which is drivable along a longwall coal conveyor in the longitudinal direction of the longwall working operation, and with at least two cutting rollers complementing or overlapping each other with their cutting sections.
2. The Prior Art
Longwall coal cutters and loaders are, in most cases, equipped with two horizontal rollers. The axes of rotation of the rollers extend parallel with the roof and perpendicular to the surface being worked, whereby the cutting sections of the cutting rollers, which are arranged one after the other in the working direction of the machine, complement or overlap one another in a way such that the material being mined is collected as the longwall cutter and loader is passing through.
The material cut loose is transferred onto a longwall conveyor for transverse conveyance. The longwall conveyor extends parallel with the traveling direction. The transverse conveyance of the material cut loose often has a hampering effect on the efficiency of such roller-equipped longwall coal cutting and loading machines because for such cross conveyance or transfer, a component of movement extending transversely to the driving direction of the mining machine has to be forced upon the material cut loose. For this purpose, the cutting tools are usually arranged on the circumference of the cutting rollers on helically extending, thread-like elements, which are intended to impart onto the material cut loose the required component of movement in the direction of the conveyor. In addition, it is customary in many cases to arrange a broaching plate or a loading chute behind the cutting roller (viewed in the direction of travel); however, such supplemental equipment is often overloaded.
With cutting rollers designed with cutting tools arranged on helical thread-like elements it is not possible to select an optimal arrangement of the cutting tools in view of the cutting process, because it is always necessary to find a compromise that ensures, on the one hand, that the material being mined is cut loose, and adequate transverse conveyance, on the other.
If the cutting tools nonetheless are to be arranged in an optimal way in view of cutting loose the material being mined, it is known in the prior art to arrange behind the cutting roller (again viewed in the direction of travel) separate transverse conveyors, for example in the form of conveyor belts, chain conveyors or similar equipment, which actively take over the required crosswise transport of the material being mined. However, such additional conveying equipment is very complicated and costly, and makes the roller-equipped cutting and loading machine susceptible to trouble accordingly.
According to the state of the art, longwall coal cutting and loading machines with vertically arranged cutting rollers are known as well, especially in Eastern Europe. The axes of rotation of the cutting rollers extend perpendicular to the roof or floor. With such vertical rollers, the bits can be arranged without taking into account in any special way the transverse conveyance because the cutting tools, when operating, generate a throwing motion in the direction of the longwall conveyor. These longwall cutters and loaders with vertical rollers, however, failed to gain wide acceptance in practical life because in spite of numerous technical tests, it has not been possible with satisfactory results to cut free, in a reliable and operationally safe way, the supporting arm carrying the vertical roller and housing the gearing required for driving the vertical roller. Within the range of the supporting arm, an uncollected strip of the material being mined is consequently left behind and obstructs the work of this longwall coal cutting and loading machine.